If true, it contradicts repeated staunch denials from Bill Shorten that he or any officials made serious approaches to the United Australia Party (UAP).
Mr Palmer slammed the Opposition Leader, describing him as a “liar” who lacks “the moral character to be Prime Minister”.
The Queensland mining magnate confirmed UAP preferences would go to the Liberal Party, but said Labor was just as keen for them.
Mr Shorten and Labor frontbencher Anthony Albanese launched an attack last week on Scott Morrison’s arrangement with Mr Palmer.
Mr Albanese even described the UAP leader as “a tosser”.
Mr Shorten has been particularly critical of the PM getting into bed with someone who has not paid millions in owed entitlements to workers at his collapsed Queensland Nickel refinery.
But Mr Palmer claimed he spoke to Labor senator Anthony Chisholm on several occasions in recent months.
“Last week, I received a phone call from him … he said he was with someone named Bill. He asked me if it was possible to get UAP preferences,” he said.
It followed a phone call from Senator Chisholm a week after the Budget, when the pair spoke in the Parliament, he claimed.
Mr Palmer says Senator Chisholm sat next to him on Budget night and asked “when we were going to get together to discuss preferences in the 2019 federal election”.
He received a phone call a week later and they agreed to meet.
It followed a lunch in Brisbane earlier this year with “a former Labor minister” who encouraged Mr Palmer to meet Senator Chisholm.
Mr Palmer said he was open to negotiations with all parties until last week when Mr Shorten began attacking UAP’s discussions with the Liberal Party in the media.
“I realised Bill Shorten was lying to the Australian people,” Mr Palmer said.
He wanted nothing more to do with Labor, believing “they were two-faced liars”.
“He’s unfit to be Prime Minister of Australia,” Mr Palmer said of Mr Shorten.
“What bothers me about the Labor Party is their willingness to lie repeatedly. It’s certainly not the quality of an individual you want to be the Prime Minister.
“Shorten’s repeated lies about preferences confirmed my judgment that he’s not morally fit to be Prime Minister.”
In response to Palmer’s blow, Mr Shorten said: “Why is it so hard for billionaires to pay taxpayers the money they owe? Why is it there’s one rule for the rest of us and another rule for him and Scott Morrison?
“If you owed the government $10,000 for longer than a year, the tax office would give you a ring, wouldn’t they? They might send you a letter, they’ll chase you up.
“But apparently, in this country, if you owe $70 million to the taxpayer, not only does the government not worry about it, it wants your preferences! In fact, it wants to elect you to the Senate.”
Mr Shorten then relinquished the microphone to his deputy Tanya Plibersek, who had been “thinking a lot” about Scott Morrison and Clive Palmer.
“The conclusion I’ve come to is they’re just the same,” Ms Plibersek said.
“Scott Morrison can afford to protect every tax loophole for the top end of town, but he can’t afford to pay childcare workers properly.
“Clive Palmer can afford to put his face on every billboard in the country, but he can’t afford to pay his workers that he ripped off.
“What really worries me is that Scott Morrison’s so desperate, he’s prepared to put his arm around Clive Palmer to do a deal, to try and cling desperately on to power. But what’s in it for Clive Palmer? What deal has Scott Morrison made?
“We know that Clive Palmer does nothing for people without expecting some return on his investment. What’s the deal here?”
Labor has sought to play down reports about its politicians making approaches to the UAP.
In addition to Senator Chisholm’s interactions, it has also been revealed that New South Wales senator Deborah O’Neill had contact with a UAP official.
Earlier today on Sky News, Mr Albanese brushed off claims about Senator Chisholm’s interactions with Mr Palmer.
He characterised him as a “senator from Queensland”. This disregards his power within the Labor Party.
Senator Chisholm was the Queensland secretary of the party and ran the 2015 state election campaign.
He was elected to the Senate in 2016.
News.com.au has approached the Labor campaign for comment.